The present invention concerns an apparatus for angularly displacing and/or moving a load suspended by ropes, said apparatus comprising a lifting trolley frame running along a girder, supported by running wheels, and of rope sheaves for the lifting ropes.
The drawback encumbering hoisting means of this type is that the load tends to swing owing to inertia forces or strong wind. In addition, it is not possible in these means to displace the load angularly, not even a small amount. In order to counteract oscillation, suspension systems have been developed which are based on changing the rope base in that the load is carried on the jib of the crane by two carriages running on tracks, their mutual distance being changeable and causing, when required, a large enough horizontal component in the support for stopping the swing.
The Patent DE-2146226 discloses a means of this kind, where the movement with relation to each other of the carriages has been implemented by means of a screw connecting them. Furthermore, the maximum distance between the carriages has been limited with a frame of framing encircling them.
In the Finnish patent application No. 821436, freedom of the load from oscillation has been arranged with two drive means, one of them reducing and the other increasing the distance between the sets of rope sheaves.
However, the drawback of these types of apparatus is that the sets of rope sheaves can only be moved towards each other or away from each other, but not in the same direction. For this reason, fine regulation of the load position is not feasible. But this would frequently be desirable, particularly when loading a ship, in which case the cargo hatch may be narrow.